Shutter mechanism



Aug. 20, 1940. F. x. sPElsER ET AL SHUTTER MECHANISM Filed Feb. 24, 1937 f fia. l

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INVENTORS @wwwa/Jawat M//v//l/f/ BY i @im MTQEY '7/ Patented Aug. 20, 1940 `UNITED STATT-:s

PATENT OFFICE lar, Germany,

assignors, by mesne assignments, to Frank Dumur, Lausanne, Switzerland Application February 24, 1937, Serial No. 127,349 In Germany February 28, 1936 4 Claims.

This invention relates to improvements in camera shutter mechanisms of the type in which the shutter is formed of two curtains which are released one after the other in order to form an exposure opening moving across the fllm. The curtains are drawn across the lm by means of spring rollers. When the curtains .snap into closed positions at the end of an exposure they make a noise similar to the noise or click made by a spring roller curtain when the spring is released to -snap the curtain into rolled up position. Such a noise in the nature of a rather loud snap or click is disturbing in connection with certain picture taking operations. It has been proposed to eliminate such noises by lnterposing springs between the curtain shafts and a xed member. Such arrangements included, however, the disadvantage that the curtains were caught before the finish of the exposure with the result that the last portion of the film was exposed longer than the first portion.

It is the object of this invention to provide dampening devices in the form of springs which engage the roller shafts tangentially, directly or indirectly, whereby to eliminate the noise referred to. As Will appear hereinafter, the action of such springs is that of glidingly or slidably engagingl and catching the roller shafts without any sudden stoppage or premature braking effect. In the accompanying drawing illustrating the invention- Fig. 1 is a View of so much of the shutter mechanism as is necessary for an understanding of the invention, parts being in section and parts broken away.

Fig. 2 is a detail diagrammatic view showing the position of the rst curtain shaft and the spring dampening device in wound up position.

Fig. 3 is a similar view showing the parts in the position at the end of an exposure or unwound.

Figs. 4 and 5 are views similar to Figures 2 and 3 but show a different arrangement.

Fig. 6 is an enlarged detail view of parts shown in Figure 1 and illustrates the invention applied to the second curtain shaft.`

Fig. 7 is a plan view of parts shown in Figure 6.

Only a brief explanation of Figure 1 is necessary because the-type of shutter shown is known in the art and is fully disclosed in Patent Number 2,122,671, July 5, 1938. The shutter consists of two curtains. The rst curtai'n 2 has its left hand edge secured to a spring roller l. The right hand edge is connected by ribbons to upper and lower ribbon drums 'l and 8. The left hand underneath the frame member edge of the follow up second curtain 3 is connected by ribbons to a similar spring roller, not shown. The right hand edge of curtain 3 is connected to a curtain roller 9. When the curtains are wound up, i. e. the shutter is closed, the first curtain 2 is stretched acrossthe film, not shown, and the second curtain 3 is wound upon the roller 9. The curtains are released in a well known manner by means of a releasing mechanism including a release shaft 23 which is delo pressed to successively release the ribbon drums and the curtain roller. The curtains in spaced relation are then drawn to the left across the exposure opening of the camera by the spring rollers.

The curtain roller 9 is secured to a shaft I8, hereinafter called the curtain shaft. The roller is engaged by a pin'2l which depends from a nipple through a circular slot 22 in the drum l. and into a hole in the end of the roller. By 20 means of certain holding, releasing and timing members which it is not necessary to explain, the shutter is opened by actuating the release shaft 23 which releases the drums so the first curtain 2 can open and thereafter the roller 9 is free to rotate so that the second curtain 3 can follow the first. It is suflicient for this invention to state that at the end of the movement of the first curtain the end of the slot 22 reaches the pin 2l Which at that time stands still. The con- 30 tact between the wall of the slot and the pins causes a noise and this invention includes means to eliminate such undesirable noise.

Referring now to Figures 2 and 3 the shaft for the rst curtain roller I8 is provided with a 35 gdisk 25 having a nose 2S. Adjacent this shaft at the lower end thereof, see Fig. 1` is mounted a rotatable arm 2'l having a recess 28 with which the nose is adapted to engage. Toa fixed pin 29 there is secured a spring 30 having a tongue 3| in tangential engagement with the arm 21 which is adapted to be moved into engagement with a fixed stop 32 to arrest anticlockwise movement of said arm. The pin 29, the spring 30, the arm 2l and the fixed stop 32 are all mounted in Figure 1 as will be understood.

When now the shaft I8 is released with the first curtain the disk 25 is moved anticlockwise and near the end of its rotative movement the nose 26 engages the recess 28 and moves the arm 21 clockwise against the spring, the arm having a cam surface 33 acting against the spring. At the end ofthe shaft movement the parts are in the position shown in Figure 3. It will therefore be seen that the blow of the curtain at the end of its movement has been eliminated because the spring has tangentially engaged the arm 21 which catches the nose 26 before the shaft `I8 has finished its unwinding movement. It is to be noted that the arm 21 moving from the position in Fig. 2 to that in- Fig. 3 gradually slows down because of the gradual compression of the spring 30. 'I'he cam surface 33 moves eccentrically about the pivot ofthe arm 21. Hence the spring is gradually compressed'y and gradually slows down the movements of the arm 21 and the shaft I8. Not only is there no blow at the end of the curtain movement but there is no rebound. When the curtain is wound up the parts again assume the position in Figure 2 and the nose 26 Y then moves the afrml21- against the stop 32.

vInFigure 4 the shaft I8 carries a disk 35 having a lnger 36 and a nose 31. A spring 38 is secured to a post 39 and is formed with a tongue 4| and a tail 42. When the curtain shaft I8 is wound up the parts are in the position shown in Figure 4 Where it will beenoted that the spring tongue 4I is in a position to tangentially engage the disk 35 while the tail 42 is' ready to engage the finger 36. This position of the spring is due to its formation. When the shaft is released it moves anticlockwise. The nose 31 now moves away from the spring and the tongue 4| moves against another xed post 40 and as a consequence the tail 42 is moved into definite tangential engagement with the disk. As the latter is about to finish its rotary movement the nger 36 engages the spring tail 42 as shown in Fig. 5 so thatthe end of the rotary movement of the disk is braked or cushioned due to the increasing resistance of the spring, the result being that the disk is stopped without any click, blow or audible impact. l

In Figures 6 and '1 the aforesaid pin 2| is provided with a spring 45 which is compressed by the end 46 of the slot 22 in the drum 1 to eliminate noise when these two elements contact at the end of the unwinding movement of the sec-v ond curtain.

It has been found that the arrangements and constructions herein disclosed cause the movements of the curtains supporting members to'be slidingly caught in a manner to eliminate noise without inue'ncing the speed of the curtain and without increasing or diminishing the exposure aperture.

We claim:

1. A focal plane shutter comprising two shutter members, rotatable members holding the same in shutter closed positions, means for rotatingsaid rotatable members to move said shutter members in spaced relation to form an exposure opening, means for stopping the rotation of said members to close the shutter after an exposure, said stoppage causing one shutter member to strike against the other shutter member, means for gradually stopping the rotation of one of said rotatable members to cause said striking operation to become practically inaudible, said mechanism com- 2O prising a compressible spring, means supporting said spring in operative relation to the said one rotatable member and means interposed between the latter and said spring and operated by the said one rotatable member to gradually compress the spring to frictionally and gradually stop the rotation of said rotatable member.

2. A focal plane shutter according to claim 1 in which the said compressible spring is a twoarmed iiat spring, said interposed means engaging one of said spring arms to move it against the other spring arm to compress said spring.

3. A focal plane shutter according to claim 1 in which said interposed means consists of a disk secured to the said one rotatable member and 

